Yonghesuchus

Yonghesuchus Temporal range: Late Triassic
Skull
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Family:	†Gracilisuchidae
Genus:	†Yonghesuchus Wu et al., 2001
Type species
†Yonghesuchus sangbiensis Wu et al., 2001

Yonghesuchus is an extinct genus of Late Triassic archosaur reptile. Remains have been found from the early Late Triassic Tongchuan Formation in Shanxi, China. It is named after Yonghe County, the county where fossils were found. Currently only one species, Y. sangbiensis, is known. The specific name refers to Sangbi Creek, as fossils were found in one of its banks.

Yonghesuchus is known from two skulls, one with an attached mandible (the holotype) and one with articulated cervical vertebrae. The holotype skull, known as IVPP V 12378, has been deformed by compression during preservation so that it has become dorsoventrally flattened. The paratype skull, known as IVPP V 12379, has also experienced damage as a result of its preservation.

The premaxilla, the bone at the front of the snout, projects past the front teeth to form a small pointed tip at the end of the snout. Behind the premaxilla is the maxilla, which contains a small depression that forms part of the antorbital fossa. This depression distinguishes Yonghesuchus from related archosauriforms such as Turfanosuchus. As in other archosauriforms such as Turfanosuchus and Euparkeria, the palate is covered in very small teeth called denticles. Behind the palate, the basisphenoid bone (which forms the floor of the braincase) is long and narrows toward the front. This is another distinguishing characteristic of Yonghesuchus, as other early archosauriforms have shorter and wider basisphenoid bones. Moreover, the entrance of the internal carotid artery, which passes through a foramen in the basisphenoid to supply blood to the brain, is in a different position than related genera. Its position is more similar to that of Dorosuchus (a euparkeriid) and more derived archosauriforms.

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